Re: [boost] cache size runtime detection

Subject: Re: [boost] cache size runtime detection
From: Rob Stewart (rob.stewart_at_[hidden])
Date: 2015-08-20 22:09:53

On August 20, 2015 6:47:42 PM EDT, Andrey Semashev <andrey.semashev_at_[hidden]> wrote:
> On 20.08.2015 22:04, Rob Stewart wrote:
> > On August 18, 2015 4:23:24 PM EDT, Andrey Semashev
> <andrey.semashev_at_[hidden]> wrote:
> >
> > This is the only thing which looks odd to me. It would be better to
> use an enumerated type, rather than bool here, or you could use the
> named constructor idiom (and make init() private).
> >
> > That is, create a default constructed features for no caching, or
> use features::complete(), say, to get one pre-populated. Otherwise,
> pass something like pre_load rather than true.
> 
> I'd prefer to allow the ability to fill the (possibly partially
> filled) 
> features object with an explicit function call.

complete() is, of course, a named function which populates the object, but it doesn't finish populating a partially loaded object. However, is there a real use case for lazily loading a subset and then loading everything? It seems unlikely to me. I'd expect usage to be either lazy access or preloading, not a combination.

> Also the static factory 
> function makes an extra copy in the following pattern:
> 
> void foo()
> {
>    static cpu::features f = cpu::features::complete();
> }

RVO should mean no copies and, besides, that's something that would be done once.

___
Rob

(Sent from my portable computation engine)